Download 40 BIOLOGY 1. Overview of Form & Function 3/16/2015

3/16/2015
CAMPBELL
BIOLOGY
TENTH
EDITION
Reece • Urry • Cain • Wasserman • Minorsky • Jackson
40
Basic Principles
of Animal Form
and Function
Lecture Presentation by
Nicole Tunbridge and
Kathleen Fitzpatrick
© 2014 Pearson Education, Inc.
1. Overview of Form & Function
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Diverse Forms, Common Challenges
 Anatomy is the biological form of an organism
 Physiology is the biological functions an
organism performs
 The comparative study of animals reveals that
form and function are closely correlated
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Evolution of Animal Size and Shape
 Physical laws govern strength,
diffusion, movement, and heat
exchange
 Properties of water limit possible
shapes for fast swimming animals
Seal
 As animals increase in size,
thicker skeletons are required for
support
Penguin
 Convergent evolution often results
in similar adaptations of diverse
organisms facing the same
challenge
Tuna
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Exchange with the Environment
 Materials such as nutrients, waste products, and
gases must be exchanged across the cell
membranes of animal cells
 Rate of exchange is proportional to a cell’s surface
area while amount of exchange material is
proportional to a cell’s volume
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 A single-celled organism living in water has sufficient
surface area to carry out all necessary exchange
 Multicellular organisms with a saclike body plan have
body walls that are only two cells thick, facilitating
diffusion of materials
Mouth
Gastrovascular
cavity
Exchange
Exchange
Exchange
0.1 mm
(a) An amoeba, a single-celled
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organism
1 mm
(b) A hydra, an animal with two
layers of cells
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 In flat animals such as tapeworms, most cells are
in direct contact with its environment
 More complex organisms are composed of
compact masses of cells with complex internal
organization
 Evolutionary adaptations such as specialized,
extensively branched or folded structures, enable
sufficient exchange with the environment
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Figure 40.4
External environment
Food
CO2
O2
Animal
body
Respiratory
system
Heart
Lung tissue (SEM)
Interstitial
fluid
Nutrients
250 µm
Mouth
Cells
Digestive
system
Anus
Unabsorbed
matter (feces)
Excretory
system
Blood vessels in
kidney (SEM)
Metabolic waste
products (nitrogenous waste)
50 µm
Lining of small
intestine (SEM)
100 µm
Circulatory
system
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 In vertebrates, the space between cells is filled
with interstitial fluid, which allows for the
movement of material into and out of cells
 A complex body plan helps an animal living in a
variable environment to maintain a relatively stable
internal environment
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Hierarchical Organization of Body Plans
 Most animals are composed of specialized cells
organized into tissues that have different
functions
 Tissues make up organs, which together make up
organ systems
 Some organs, such as the pancreas, belong to
more than one organ system
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Table 40.1a
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Table 40.1b
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2. Tissues
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Exploring Structure and Function in
Animal Tissues
 Different tissues have different structures that are
suited to their functions
 Tissues are classified into four main categories:
epithelial, connective, muscle, and nervous
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Epithelial Tissue
 Epithelial tissue covers the outside of the body
and lines the organs and cavities within the body
 It contains cells that are closely joined
 The shape of epithelial cells may be cuboidal (like
dice), columnar (like bricks on end), or squamous
(like floor tiles)
 The arrangement of epithelial cells may be simple
(single cell layer), stratified (multiple tiers of cells),
or pseudostratified (a single layer of cells of
varying length)
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Figure 40.5a
Epithelial Tissue
Stratified
squamous
epithelium
Apical
surface
Basal
surface
Cuboidal
epithelium
Simple columnar
epithelium
Simple
squamous
epithelium
Pseudostratified
columnar
epithelium
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Figure 40.5aa
Polarity of epithelia
Lumen
Apical surface
10 µm
Basal surface
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Connective Tissue
 Connective tissue mainly binds and supports
other tissues
 It contains sparsely packed cells scattered
throughout an extracellular matrix
 The matrix consists of fibers in a liquid, jellylike, or
solid foundation
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 There are three types of connective tissue
fiber, all made of protein
 Collagenous fibers provide strength and flexibility
 Reticular fibers join connective tissue to adjacent tissues
 Elastic fibers stretch and snap back to their original length
 Connective tissue contains cells, including:
 Fibroblasts that secrete the protein of extracellular fibers
 Macrophages that are involved in the immune system
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In vertebrates, the fibers and foundation combine
to form six major types of connective tissue
1. Loose connective tissue binds epithelia to underlying
tissues and holds organs in place
2. Fibrous connective tissue is found in tendons, which
attach muscles to bones, and ligaments, which connect
bones at joints
3. Bone is mineralized and forms the skeleton
4. Adipose tissue stores fat for insulation and fuel
5. Blood is composed of blood cells and cell fragments in
blood plasma
6. Cartilage is a strong and flexible support material
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Figure 40.5b
Connective Tissue
Blood
Loose connective tissue
Plasma
White
blood
cells
120 µm
55 µm
Collagenous fiber
Cartilage
Elastic fiber
Fibrous connective tissue
Red blood cells
30 µm
100 µm
Chondrocytes
Chondroitin sulfate
Adipose tissue
700 µm
Central
canal
Osteon
Fat droplets
150 µm
Bone
Nuclei
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Muscle Tissue
 Muscle tissue is responsible for nearly all types of body
movement
 Muscle cells consist of filaments of the proteins actin and
myosin, which together enable muscles to contract
 It is divided in the vertebrate body into three types
 Skeletal muscle, or striated muscle, is responsible for
voluntary movement
 Smooth muscle is responsible for involuntary body
activities
 Cardiac muscle is responsible for contraction of the heart
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Figure 40.5c
Muscle Tissue
Skeletal muscle
Nuclei
Muscle
fiber
Sarcomere
100 µm
Smooth muscle
Nucleus
Muscle
fibers
Cardiac muscle
25 µm
Nucleus Intercalated
disk
25 µm
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Nervous Tissue
 Nervous tissue functions in the receipt, processing, and
transmission of information
 Nervous tissue contains neurons, or nerve cells, that
transmit nerve impulses & Glial cells, or glia, support cells
Nervous Tissue
Glia
Neurons
Neuron:
Dendrites
Cell body
Glia
15 µm
Axons of
neurons
40 µm
Axon
(Fluorescent LM)
Blood
vessel
(Confocal LM)
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Coordination and Control
 Control and coordination within a body depend on
the endocrine system and the nervous system
 The endocrine system transmits chemical signals
called hormones to receptive cells throughout the
body via blood
 A hormone may affect one or more regions
throughout the body
 Hormones are relatively slow acting, but can have
long-lasting effects
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Figure 40.6
(a) Signaling by hormones
STIMULUS
(b) Signaling by neurons
STIMULUS
Endocrine
cell
Cell body
of neuron
Axon
Nerve
impulse
Hormone
Signal travels
everywhere.
Blood
vessel
Signal travels
to a specific
location.
Nerve
impulse
Axons
Response
Response
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 The nervous system transmits information
between specific locations
 The information conveyed depends on a signal’s
pathway, not the type of signal
 Nerve signal transmission is very fast
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3. Regulation & Homeostasis
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Feedback control maintains the internal
environment in many animals
 Faced with environmental fluctuations, animals manage
their internal environment by either regulating or
conforming
Regulating and Conforming
 A regulator uses internal control mechanisms to control
internal change in the face of external fluctuation
 A conformer allows its internal condition to vary with
certain external changes
 Animals may regulate some environmental variables
while conforming to others
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Figure 40.7
40
Body temperature (C)
River otter (temperature regulator)
30
20
Largemouth bass
(temperature conformer)
10
0
0
10
20
30
40
Ambient (environmental)
temperature (C)
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Homeostasis
 Organisms use homeostasis to maintain a “steady state”
or internal balance regardless of external environment
 In humans, body temperature, blood pH, and glucose
concentration are each maintained at a constant level
Mechanisms of Homeostasis
 Mechanisms of homeostasis moderate changes in the
internal environment
 For a given variable, fluctuations above or below a set
point serve as a stimulus; these are detected by a sensor
and trigger a response
 The response returns the variable to the set point
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Figure 40.8
Room temperature
increases.
Thermostat turns
heater off.
Room temperature
decreases.
ROOM
TEMPERATURE
AT 20C (set point)
Room temperature
increases.
Thermostat
turns heater on.
Room temperature
decreases.
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Feedback Control in Homeostasis
 Homeostasis in animals relies largely on negative
feedback, which helps return a variable to a normal
range
 Positive feedback amplifies a stimulus and does not
usually contribute to homeostasis in animals
Alterations in Homeostasis
 Set points and normal ranges can change with age or
show cyclic variation
 In animals and plants, a circadian rhythm governs
physiological changes that occur roughly every 24 hours
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Body
temperature
Melatonin
concentration
37.1
60
36.9
40
36.7
20
36.5
0
2
6
PM
PM
10
2
6
10
PM
AM
AM
AM
Melatonin concentration
in blood (pg/mL)
Core body temperature (C)
Figure 40.9
Time of day
(a) Variation in core body temperature and melatonin
concentration in blood
Start of
melatonin secretion
Midnight
Greatest
muscle
strength
Lowest
heart rate
Lowest body
temperature
6 PM
6 AM
Most rapid
rise in blood
pressure
Fastest
reaction time
Noon
Highest risk
of cardiac arrest
(b) The human circadian clock
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 Homeostasis can adjust to changes in external
environment, a process called acclimatization
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Homeostatic processes for thermoregulation
involve form, function, and behavior
 Thermoregulation is the process by which animals
maintain an internal temperature within a tolerable range
Endothermy and Ectothermy
 Endothermic animals generate heat by metabolism;
birds and mammals are endotherms
 Ectothermic animals gain heat from external sources;
ectotherms include most invertebrates, fishes,
amphibians, and nonavian reptiles
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 Endotherms can maintain a stable body temperature even in
the face of large fluctuations in environmental temperature
 Endothermy is more energetically expensive than ectothermy
 In general, ectotherms tolerate greater variation in internal
temperature
(a) A walrus, an endotherm
(b) A lizard, an ectotherm
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Variation in Body Temperature
 The body temperature of a poikilotherm varies with
its environment
 The body temperature of a homeotherm is
relatively constant
 The relationship between heat source and body
temperature is not fixed (that is, not all
poikilotherms are ectotherms)
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Figure 40.12
Balancing Heat Loss and Gain
 Organisms exchange heat by four physical processes:
radiation, evaporation, convection, and conduction
Radiation
Evaporation
Convection
Conduction
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 Heat regulation in mammals often involves the
integumentary system: skin, hair, and nails
 Five adaptations help animals thermoregulate
 Insulation
 Circulatory adaptations
 Cooling by evaporative heat loss
 Behavioral responses
 Adjusting metabolic heat production
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Insulation
 Insulation is a major thermoregulatory adaptation
in mammals and birds
 Skin, feathers, fur, and blubber reduce heat flow
between an animal and its environment
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Circulatory Adaptations
 Regulation of blood flow near the body surface
significantly affects thermoregulation
 Many endotherms and some ectotherms can alter
the amount of blood flowing between the body
core and the skin
 In vasodilation, blood flow in the skin increases,
facilitating heat loss
 In vasoconstriction, blood flow in the skin
decreases, lowering heat loss
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 The arrangement of blood vessels in many marine
mammals and birds allows for countercurrent
exchange
 Countercurrent heat exchangers transfer heat
between fluids flowing in opposite directions and
thereby reduce heat loss
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Figure 40.13
Bottlenose
dolphin
Canada
goose
1
Vein
Artery
1
3
Artery
Vein
35C
33
30
27
20
18
10
9
3
3
2
Key
Warm blood
Cool blood
2
Blood flow
Heat transfer
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Cooling by Evaporative Heat Loss
 Many types of animals lose heat through
evaporation of water from their skin
 Sweating or bathing moistens the skin, helping to
cool an animal down
 Panting increases the cooling effect in birds and
many mammals
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Behavioral Responses
 Both endotherms and
ectotherms use behavioral
responses to control body
temperature
 Some terrestrial
invertebrates have
postures that minimize or
maximize absorption of
solar heat
 Honeybees huddle
together during cold
weather to retain heat
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Adjusting Metabolic Heat Production
 Thermogenesis is the adjustment of metabolic
heat production to maintain body temperature
 Thermogenesis is increased by muscle activity
such as moving or shivering
 Nonshivering thermogenesis takes place when
hormones cause mitochondria to increase their
metabolic activity
 Some ectotherms can also shiver to increase body
temperature
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Figure 40.15
PREFLIGHT
40
PREFLIGHT
WARM-UP
FLIGHT
Thorax
Temperature ( C)
Thorax
35
Abdomen
30
Abdomen
25
0
2
Time from onset of warm-up (min)
4
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Figure 40.16
Results
O2 consumption (mL O2/hr•kg)
120
100
80
60
40
20
0
0
5
10
15
20
25
30
Contractions per minute
35
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Acclimatization in Thermoregulation
 Birds and mammals can vary their insulation to
acclimatize to seasonal temperature changes
 When temperatures are subzero, some
ectotherms produce “antifreeze” compounds to
prevent ice formation in their cells
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Physiological Thermostats and Fever
 Thermoregulation in mammals is controlled by a region
of the brain called the hypothalamus
 The hypothalamus triggers heat loss or heat generating
mechanisms
 Fever, a response to some infections, reflects an
increase in the normal range for the biological
thermostat
 Some ectothermic organisms seek warmer
environments to increase their body temperature in
response to certain infections
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Figure 40.17
Thermostat in
hypothalamus
activates cooling
mechanisms.
Response: Blood
vessels in skin dilate.
Response:
Sweat
Body temperature
increases.
Body temperature
decreases.
NORMAL BODY
TEMPERATURE
(approximately
36–38C)
Body temperature
increases.
Body temperature
decreases.
Response: Shivering
Response: Blood
vessels in skin
constrict.
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Thermostat in
hypothalamus
activates
warming
mechanisms.
4. Bioenergetics
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Energy requirements are related to animal
size, activity, and environment
 Bioenergetics is the overall flow and transformation of
energy in an animal
 It determines how much food an animal needs and it
relates to an animal’s size, activity, and environment
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Quantifying Energy Use
 Metabolic rate is the amount of energy an animal
uses in a unit of time
 Metabolic rate can be determined by measuring:
 An animal’s heat loss
 The amount of oxygen consumed or carbon dioxide
produced
 Measuring energy content of food consumed and
energy lost in waste products
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Minimum Metabolic Rate and Thermoregulation
 Basal metabolic rate (BMR) is the metabolic rate
of an endotherm at rest at a “comfortable”
temperature
 Standard metabolic rate (SMR) is the metabolic
rate of an ectotherm at rest at a specific
temperature
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Size and Metabolic Rate
 Metabolic rate is proportional to body mass to the
power of three quarters (m3/4)
 Smaller animals have higher metabolic rates per
gram than larger animals
 The higher metabolic rate of smaller animals leads
to a higher oxygen delivery rate, breathing rate,
heart rate, and greater (relative) blood volume,
compared with a larger animal
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Figure 40.20a
103
BMR (L O2/hr) (log scale)
Elephant
Horse
102
Human
Sheep
10
Dog
Cat
1
10−1
Shrew
10−2
10 −3
Rat
Ground squirrel
Mouse
Harvest mouse
10 −2
10 −1
1
10
102
103
Body mass (kg) (log scale)
(a) Relationship of basal metabolic rate (BMR) to body
size for various mammals
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Figure 40.20b
8
Shrew
7
BMR (L O2/hr•kg)
6
5
4
3
Harvest mouse
2
Mouse
Rat
1
Ground
squirrel
0
10 −3
10 −2
10−1
Cat
1
Sheep
Elephant
Human
Dog
Horse
10
10 2
10 3
Body mass (kg) (log scale)
(b) Relationship of BMR per kilogram of body mass to
body size
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Torpor and Energy Conservation
 Torpor is a physiological state in which activity is
low and metabolism decreases
 Torpor enables animals to save energy while
avoiding difficult and dangerous conditions
 Hibernation is long-term torpor that is an
adaptation to winter cold and food scarcity
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